The fgrep (fast grep) utility searches files for a character string and prints all lines that contain that string. fgrep is different from grep(1) and egrep(1) because it searches for a string, instead of searching for a pattern that matches an expression. It uses a fast and compact algorithm.

The characters $, *, [, ^, |, (, ), and \ are interpreted literally by fgrep, that is, fgrep does not recognize full regular expressions as does egrep. Since these characters have special meaning to the shell, it is safest to enclose the entire string in single quotes ´... ´.

If no files are specified, fgrep assumes standard input. Normally, each line found is copied to the standard output. The file name is printed before each line found if there is more than one input file.

The following options are supported:

-b

Precede each line by the block number on which it was found. This can be useful in locating block numbers by context (first block is 0).

-c

Print only a count of the lines that contain the pattern.

-e pattern_list

Search for a string in pattern-list (useful when the string begins with a -).

-f pattern-file

Take the list of patterns from pattern-file.

-h

Suppress printing of files when searching multiple files.

-i

Ignore upper/lower case distinction during comparisons.

-l

Print the names of files with matching lines once, separated by new-lines. Does not repeat the names of files when the pattern is found more than once.

-n

Precede each line by its line number in the file (first line is 1).

-s

Work silently, that is, display nothing except error messages. This is useful for checking the error status.

-v

Print all lines except those that contain the pattern.

-x

Print only lines matched entirely.

The following operands are supported:

file

A path name of a file to be searched for the patterns. If no file operands are specified, the standard input will be used.

/usr/bin/fgrep

/usr/xpg4/bin/fgrep

See largefile(5) for the description of the behavior of fgrep when encountering files greater than or equal to 2 Gbyte ( 2³¹ bytes).

See environ(5) for descriptions of the following environment variables that affect the execution of fgrep: LC_COLLATE, LC_CTYPE, LC_MESSAGES, and NLSPATH.

The following exit values are returned:

0

if any matches are found

1

if no matches are found

2

for syntax errors or inaccessible files (even if matches were found).

See attributes(5) for descriptions of the following attributes:

/usr/bin/fgrep

/usr/xpg4/bin/fgrep

ed(1), egrep(1), grep(1), sed(1), sh(1), attributes(5), environ(5), largefile(5), XPG4(5)

Ideally there should be only one grep command, but there is not a single algorithm that spans a wide enough range of space-time tradeoffs.

Lines are limited only by the size of the available virtual memory.

/usr/xpg4/bin/fgrep